1. Cut crosswise slits into the chicken breasts, 1/2 inch apart and about three quarters of the way into the chicken, being very careful not to cut all the way through the chicken.  You want the bottom of the chicken breast to stay intact so the top can fan open without it falling apart.
2. Using a knife or pastry brush, slather each breast generously with pesto.
3. Stuff each slit with a slice of mozzarella and 3 – 4 pieces of sun-dried tomato.  Season generously with salt and pepper.
4. Place stuffed chicken on a sturdy trivet or a pan with holes in the bottom.  
5. Note: If you don’t have either, simply use the trivet you have, place a piece of tinfoil on top of it to make it more stable, and poke holes into it with a knife or fork so that the extra juices of the chicken can drain while cooking.
6. Pour 1 cup of water into the pressure cooker pot and place the trivet with the chicken inside the pot.  
7. Secure the lid and turn pressure release knob to a sealed position.  Cook at high pressure for 5 minutes.
8. When pressure cooking is complete, use a natural release for 10 minutes, then quick release any remaining pressure.
9. To serve, place a handful of fresh spinach on a plate and top with bacon or prosciutto, chopped avocado, and sliced almonds.  
10. Place the chicken breast next to the spinach and drizzle the entire dish with balsamic glaze.  Garnish with a chiffonade of basil.

Make Ahead Instructions

1. Brush the chicken with pesto and fill with tomatoes and mozzarella.  Store in the refrigerator in an airtight container for up to 24 hours in advance.

Freezer Instructions

1. I suspect you could make the chicken up ahead of time, freeze on a sheet pan, then wrap with plastic wrap and place in a freezer safe ziploc bag.  I haven’t tested this yet, but I’ve frozen mozzarella before and felt it was fine afterwards.
2. To cook from frozen, increase the cook time to 8 minutes.